chore: fix license (#2455)

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🛠️ Fixes #<issue_number_goes_here>

docs/en/getting-started/quickstart/go/quickstart_test.go

@@ -1,3 +1,5 @@
+// Copyright 2025 Google LLC
+//
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -9,6 +11,7 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+
 package main
 
 import (